The goal of the Mouse Breeding Core is to provide mice and hamsters to Program investigators in a cost-effective and dependable manner. Both control and dystrophic mice and hamsters will be bred to maintain a colony of sufficient size such that ample animals of specified age can be supplied to each of the research projects in this Program. This Core has been in operation for early two years, and has been run by Dr. Clemens during this time. Support has previously been derived from a parent-run foundation, as part of the DMDRC. Setting of priorities of the Core will be done by Dr. Clemens, with the Program Director(Dr. Hoffman) arbitrating any conflicts with regards mouse or hamster requirements. Day-to-day operation of the Core, including distribution of mice and hamsters, will be done by a technician, Ms. Christy Bruton, who has been responsible for the Core to date.